The poll, conducted June 5-8, finds Congress's job approval at 16 percent, its lowest point in a midterm election year since Gallup began tracking the metric in 1974. Satisfaction with the direction of the country comes in at a paltry 23 percent, just a point above its 2010 midterm year low.

The poll comes just days after Tea Party-backed candidate David Brat trounced House Majority Leader Eric Cantor in a stunning GOP primary upset.

Its findings, which also included middling approval numbers for President Obama and enduringly high levels of economic concern, put incumbents on uneven footing this election cycle. Past years with similarly deflated numbers, including 1982, 2006, and 2010, have resulted in a large turnover in Congress.

In another recent poll, Gallup found that 50 percent of voters believed their own member of Congress deserved re-election. That's a far sunnier measure than congressional approval as whole, reflecting a typical heightened regard for local politicians, but it's also the indicator's weakest showing since 1992, when it was 48 percent.